The present invention relates to an appliance spin control and method adaptable to floor structure.
Washing machine appliances include washing baskets that spin about a basket axis during one or more washing machine cycles. Weak, unstable or unlevel supporting floors often cause a washing machine to become unbalanced, and therefore it is necessary to provide a system which compensates for a lack of rigidity, stability, or levelness of the floor below the machine. Because the floor condition will vary from one washing machine installation to another, it is desired in accordance with the present invention to have the machine automatically adjust the rotational speed of the basket in relation to the characteristics of the supporting floor.
Therefore a primary object of the present invention is the provision of an improved appliance spin control and method which automatically adjusts the spin of the washing basket in response to the particular characteristics of the supporting floor structure.
A further object of the present invention is the provision of a spin balance control that utilizes a vibration sensor attached to the washing machine cabinet for sensing the vibration of the cabinet during rotation of the washing machine basket.
A further object of the present invention is the provision of a spin control which adjusts the rotational speed of the basket to prevent unbalance vibration for each variation of supporting floor structure.
A further object of the present invention is the provision of an improved appliance spin control and method which are economical in manufacture, durable in use, and efficient in operation.
The foregoing objects may be achieved by a washing machine spin balancing system comprising in combination a support floor and a washing machine cabinet supported on the support floor. A washing machine basket is mounted within the cabinet for rotation about a basket axis. A drive is connected to the basket for causing rotation of the basket. The drive is capable of rotating the basket at a high rotational speed or alternative at one or more low rotational speeds slower than the high rotational speed. A vibration sensor is attached to the cabinet for sensing the vibration of the cabinet. A controller is connected to the sensor and to the drive. The controller is adapted to cause the drive to rotate the basket at the high rotation speed in response to the vibration sensor sensing less than a predetermined amount of vibration of the cabinet. The controller is adapted to cause the drive to rotate the basket at a low rotational speed in response to the vibration sensor sensing more than the predetermined amount of vibration of the cabinet.
According to one feature of the invention the vibration sensor comprises an accelerometer. However, the particular structure of the accelerometer or vibration sensor may vary without detracting from the invention. All that is required is that the vibration sensor be capable of sensing the vibration of the washing machine cabinet.
According to another feature of the invention, the slower rotational speed is approximately 67% of the higher rotational speed.
The foregoing control system permits the reduction of the rotational speed of the basket in response to various types of floors. A floor with imperfections causes the threshold unbalance vibration to be reached more easily at the higher rotational speed than would be the case if the floor were without these imperfections.
According to another feature of the invention, the method comprises placing the washing machine cabinet on a floor having unique characteristics of stability, strength, and levelness which affect the magnitude of vibration of the washing machine cabinet in response to rotation of the basket within the washing machine cabinet. A drive is used to rotate the washing machine basket at a first rotational speed. During rotation a sensor senses the magnitude of vibration of the washing machine cabinet. A controller connected to the vibration sensor and to the drive causes the drive to reduce the rotational speed of the basket to a second rotational speed slower than the first rotational speed in response to the sensed magnitude of vibration of the washing machine basket exceeding a predetermined magnitude of vibration.